Voile is correct - the example returns 6 because from the input (-2, 1, -3, 4, -1, 2, 1, -5, 4) you have to find the sequence which yields the highest sum.

That (as Voile correctly states) is "4, -1, 2, 1" because 4 - 1 = 3, then 3 + 2 = 5, then 5 + 1 = 6. There are negative numbers before (-3) and after (-5) this sub-sequence so the sub-sequence in the result is the yields the highest sum.